The atmosphere is made up of five layers: 1. The troposphere 2. The stratosphere 3. The mesosphere 4. The thermosphere 5. The exosphere. The composition of gases in each layer is very different.
Exosphere
64,000 km Thermosphere 640 km Mesosphere 80 km Ozone layer Stratosphere 50 km Troposphere z Fig. 22.4.4
The layers of the atmosphere
Earth 16 km
Learn more about UV rays in Biological World 4.3
1. Troposphere: clouds and weather systems form up to 16 km above the Earth. Above only 6 km, the air becomes so thin that mountain climbers have to carry special equipment to help them breathe. Some military planes can fly above this height, but most planes stay within the troposphere.
2. Stratosphere: the ozone layer is found in this layer of the atmosphere. Ozone gas protects the Earth from harmful UV rays from the Sun.
3. Mesosphere: this layer makes up less than five per cent of the atmosphere. Space debris burns up as it enters this layer and shooting stars can be seen here. The coldest place on Earth is at the top of the mesosphere.
Learn more about aurorae in Physical World 18.1
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4. Thermosphere: this layer is only a tiny fraction of the Earth’s atmosphere but it absorbs a lot of solar radiation and temperatures can get very hot here. The charged particles in this layer are influenced by the Earth’s magnetic field and sometimes produce beautiful aurorae.
5. Exosphere: this uppermost layer is where the Earth’s atmosphere merges with space.
